Removes diacritics from input string

REMOVE_DIACRITICS.sql

-- Removes diacritics from input string
-- Author : sfaut <https://github.com/sfaut>
-- Publication date : 2023-01-07
-- Tested with MySQL 8.0.31 (@@sql_mode='ANSI,TRADITIONAL')

DELIMITER ;;

CREATE FUNCTION REMOVE_DIACRITICS(input TEXT) RETURNS TEXT CHARSET utf8mb4
DETERMINISTIC
COMMENT 'Removes diacritics from input string'
BEGIN
	DECLARE length INTEGER UNSIGNED DEFAULT CHAR_LENGTH(input);
	DECLARE i INTEGER UNSIGNED DEFAULT 0;
	DECLARE c VARCHAR(1); -- Pas de CHAR(1) car perte espace
	DECLARE p INT UNSIGNED;
	DECLARE buffer TEXT DEFAULT '';
	DECLARE with_diacritics TINYTEXT DEFAULT    'àáâãäåæçèéêëìíîïñòóôõöøšùúûüýÿžÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÑÒÓÔÕÖØŠÙÚÛÜÝŸŽ';
	DECLARE without_diacritics TINYTEXT DEFAULT 'aaaaaaaceeeeiiiinoooooosuuuuyyzAAAAAAACEEEEIIIINOOOOOOSUUUUYYZ';

	WHILE i < length DO
		SET i = i + 1;
		SET c = SUBSTRING(input FROM i FOR 1);
		SET p = POSITION(c IN with_diacritics COLLATE utf8mb4_0900_as_cs);
		IF p > 0 THEN
			SET c = SUBSTRING(without_diacritics FROM p FOR 1);
		END IF;
		SET buffer = CONCAT(buffer, c);
	END WHILE;

	RETURN buffer;
END;;